1. Technical Field
The present invention relates to an apparatus for helping to protect a vehicle occupant during a crash condition. More particularly, the present invention relates to a vehicle seat belt system having a load limiter.
2. Description of the Prior Art
U.S. Pat. No. 6,076,894 discloses a seat belt system having two shoulder belts and two lap belts. Each shoulder belt extends from an associated shoulder belt retractor, which is fixed relative to an upper portion of a vehicle seat, downward to a buckle assembly. Left and right lap belts are also connected with the vehicle seat and through the buckle assembly.
It is known to use a load limiter to limit the load experienced by a vehicle occupant due to a length of belt webbing restraining the occupant in a crash condition. The load limiter may include a deformable torsion bar.
The present invention relates to an apparatus for helping to protect a vehicle occupant in a vehicle seat. The apparatus comprises a first length of belt webbing for extending over a vehicle occupant and a second length of belt webbing for extending over the vehicle occupant. A first spool is supported for rotation in a belt retraction direction and an opposite belt withdrawal direction, a portion of the first length of belt webbing being wound on the first spool. A second spool is supported for rotation in a belt retraction direction and an opposite belt withdrawal direction, a portion of the second length of belt webbing being wound on the second spool. The apparatus includes a mechanism for blocking rotation of the first and second spools in the belt withdrawal direction until a predetermined force is applied to the first and second spools and for permitting rotation of the first and second spools in the belt withdrawal direction when a force above the predetermined force is applied to the first and second spools. The mechanism drivingly interconnects the first and second spools and permits rotation of one of the first and second spools in the belt withdrawal direction after blocking rotation in the belt withdrawal direction without causing rotation of the other spool in the belt withdrawal direction.
In one embodiment, the mechanism includes a load limiter for reducing the maximum load experienced by the vehicle occupant through the first and second lengths of belt webbing, a first actuatable one way clutch connected between the first spool and the load limiter, and a second actuatable one way clutch connected between the second spool and the load limiter.